1. Field of the Invention
It is well known that a 3D (three-dimensional) image display system causes the viewer to view a stereoscopic view by displaying a right eye image and a left eye image alternately on a screen of a 3D display in a predetermined period and comprising liquid crystal shutter glasses, mounted by a viewer, in which a right eye liquid crystal and a left eye liquid crystal alternately transmit light and do not transmit light, respectively, in synchronization with the predetermined period. The present invention relates to a driving apparatus for driving the liquid crystal shutter glasses. The present invention further relates to a spatial transmission signal transmitting apparatus for transmitting a spatial transmission signal fed to the liquid crystal shutter glasses.
2. Description of the Prior Art
In order to inform liquid crystal shutter glasses of switching between a right eye image (R) and a left eye image (L) on the side of a 3D display , there is a technique using an infrared signal. As the specific construction, construction shown in FIG. 16 has been considered. In the construction, a clock having a frequency of 455 to 500 KHz is changed into a clock having a frequency of approximately 30 to 57 KHz by a divider 501, and the clock having a frequency of 30 to 57 KHz is used as a carrier. A gate signal generating circuit 502 receives the clock which is the carrier, and detects an edge of a signal representing switching between a left eye image and a right eye image which are alternately displayed on a screen (hereinafter referred to as an L/R polarity switching signal) by the clock, to generate a signal representing distinction between a right eye image and a left eye image (hereinafter referred to as a gate signal) on the basis of the edge. An AND element 503 carries out the conjunction between the clock which is the carrier and the gate signal, to generate an LED driving pulse. The LED driving pulse is fed to an LED light emitting unit (not shown), so that the LED light emitting unit emits light (blinks) depending on the driving pulse.
In the above-mentioned construction, however, a difference (jitter t) between the edge of the L/R polarity switching signal and a rise edge of the gate signal is a maximum of one pulse of clock having a frequency of 30 to 57 KHz (approximately 20 xcexcs) which is the carrier. The jitter is relatively large. When a signal having the jitter is reproduced (decoded) on the side of the liquid crystal shutter glasses, jitter based on a clock on the side of the liquid crystal shutter glasses is further added. Consequently, the width of the total jitter becomes larger, so that various problems arise. For example, a shutter switching portion flickers.
In cases such as that a person passes between the 3D display and the viewer, the infrared signal may, in some cases, be blocked for several seconds. In such a case, the liquid crystal shutter glasses stop operating in a state where they transmit the right eye image (R) or a state where they transmit the left eye image (L), resulting in a state where 3D view is impossible. The conventional liquid crystal shutter glasses cannot cope with plurality of frequencies. For example, they cope with, if the timing of switching (field frequency) between the right eye image (R) and the left eye image (L) is 120 Hz, only the frequency of 120 Hz, and they cope with, if it is 60 Hz, only the frequency of 60 Hz. That is, they cannot cope with various types of 3D displays that differ in field frequency.
In the liquid crystal shutter glasses, a liquid crystal which does not transmit light when a predetermined minus voltage and a predetermined plus voltage are applied thereto, while transmitting light when a voltage of zero volt is applied has been conventionally used. Since the response speed thereof in a case where the liquid crystal is changed from a state where it does not transmit light to a state where it transmits light upon application of a voltage of zero volt is low, however, the liquid crystal does not sufficiently transmit light even after a vertical blanking period, as shown in FIG. 18, so that the upper part of a screen looks dark.
The present invention has been made in view of the above-mentioned circumstances and has for its object to provide an apparatus for driving liquid crystal shutter glasses capable of maintaining a shutter operation even if a signal representing shutter timing in the liquid crystal shutter glasses is blocked, to cope with various types of 3D displays which differ in field frequency, and to prevent the upper part of a screen from looking dark.
An apparatus for driving liquid crystal shutter glasses according to the present invention is characterized by comprising receiving means for receiving a spatial transmission signal generated on the basis of a signal representing switching between right and left eye images, means for acquiring data relating to shutter timing in the liquid crystal shutter glasses from the received spatial transmission signal, and means for causing the liquid crystal shutter glasses to perform a shutter operation using the acquired data relating to shutter timing.
According to the above-mentioned construction, the spatial transmission signal is generated on the basis of the signal representing switching between right and left eye. images, and the data relating to shutter timing in the liquid crystal shutter glasses is acquired from the spatial transmission signal on the side of the liquid crystal shutter glasses, to cause the liquid crystal shutter glasses to perform the shutter operation. That is, if a frequency for switching between right and left eye images changes, the spatial transmission signal changes depending on the change, so that the change can be detected on the side of the liquid crystal shutter glasses. Accordingly, the liquid crystal shutter glasses can cope with various types of 3D displays that differ in field frequency.
An apparatus for driving liquid crystal shutter glasses according to the present invention is characterized by comprising receiving means for receiving a spatial transmission signal generated on the basis of a signal representing switching between right and left eye images, means for acquiring data relating to shutter timing in the liquid crystal shutter glasses from the received spatial transmission signal, means for holding the acquired data relating to shutter timing, and means capable of causing the liquid crystal shutter glasses to perform a shutter operation using the held data relating to shutter timing under predetermined conditions.
According to the above-mentioned construction, the spatial transmission signal is blocked, so that the shutter operation in the liquid crystal shutter glasses can be continued (self-contained) even if the data relating to shutter timing in the liquid crystal shutter glasses cannot be generated, thereby making it possible to prevent a screen from flickering when the signal is blocked.
An apparatus for driving liquid crystal shutter glasses according to the present invention is characterized by comprising receiving means for receiving a spatial transmission signal generated on the basis of a signal representing switching between right and left eye images, means for acquiring data relating to shutter timing in the liquid crystal shutter glasses from the received spatial transmission signal, means for generating decision data relating to shutter timing to be fed to the liquid crystal shutter glasses on the basis of predetermined conditions from the data relating to shutter timing newly obtained in succession and holding the generated decision data, and means capable of causing, when no decision data is generated because the predetermined conditions are not satisfied, the liquid crystal shutter glasses to perform a shutter operation using the held decision data.
In the above-mentioned construction, the apparatus for driving liquid crystal shutter glasses may be so constructed that predetermined processing is executed, respectively, in a state where the field frequency is indefinite, a state where the field frequency is definite, and a state where the field frequency is maintained, and the transition from each of the three states to other states occurs depending on the result of the execution, the state where the field frequency is indefinite is a state where the shutter operation is stopped, in which processing for judging whether or not the predetermined conditions are satisfied and generating the decision data when the conditions are satisfied is performed, the state where the field frequency is definite is a state where the shutter operation is performed on the basis of the decision data successively determined, in which the decision data is generated and held when the predetermined conditions are satisfied, while the transition to the state where the field frequency is maintained occurs when the predetermined conditions are not satisfied, and the state where the field frequency is maintained is a state where the shutter operation is continued on the basis of the held decision data, in which the transition to the state where the field frequency is definite occurs when the predetermined conditions are satisfied, while the transition to the state where the field frequency is indefinite occurs when the shutter operation is continued for a predetermined time period without satisfying the predetermined conditions.
In such construction, if the shutter timing obtained from the spatial transmission signal satisfies the predetermined conditions, the state where the field frequency is definite occurs, so that the shutter operation is performed on the basis of the decision data successively determined. When the signal is blocked from any cause in such a state, the transition to the state where the field frequency is maintained occurs. If the shutter timing satisfies the predetermined conditions in this state, the transition to the state where the field frequency is definite occurs. On the other hand, when the shutter timing does not satisfy the predetermined conditions (the conditions are not satisfied if a state where the signal is blocked continues), the shutter operation is continued on the basis of the held decision data. During this period, the transition to the state where the field frequency is definite occurs when the shutter timing satisfies the predetermined conditions, while the transition to the state where the field frequency is indefinite occurs when such a state where the shutter operation is continued continues for a predetermined time period, so that the shutter operation in the liquid crystal shutter glasses is stopped.
An apparatus for driving liquid crystal shutter glasses according to the present invention is an apparatus for driving liquid crystal shutter glasses using a liquid crystal which does not transmit light when a predetermined minus voltage and a predetermined plus voltage are applied, while transmitting light when a voltage of zero volt is applied, characterized by comprising receiving means for receiving a spatial transmission signal generated on the basis of a signal representing switching between right and left eye images, means for acquiring data relating to shutter timing in the liquid crystal shutter glasses from the received spatial transmission signal, and means for causing the liquid crystal shutter glasses to perform a shutter operation by advancing the timing at which a voltage of zero volt is applied by a time period previously set in consideration of a time period required for the liquid crystal to sufficiently transmit light while using the acquired data relating to shutter timing.
In the above-mentioned construction, when a voltage of zero volt is applied (the liquid crystal is brought into a state where it transmits light), the timing is advanced. Even if the response speed in a case where the liquid crystal enters the state where it transmits light is low, therefore, the liquid crystal can sufficiently transmit light before a vertical blanking period is terminated, thereby making it possible to prevent the upper part of a screen from looking dark.
An object of the present invention is to provide a spatial transmission signal transmitting apparatus for liquid crystal shutter glasses that can reduce jitter.
In order to solve the above-mentioned problem, a spatial transmission signal transmitting apparatus for liquid crystal shutter glasses according to the present invention is a spatial transmission signal transmitting apparatus for liquid crystal shutter glasses for transmitting a spatial transmission signal fed to the liquid crystal shutter glasses on the basis of a signal representing switching between a left eye image and a right eye image which are alternately displayed on a screen, characterized by comprising spatial transmission signal generating means driven by a driving pulse, driving pulse generating means for generating the driving pulse by modulating a clock having a first frequency using a signal representing distinction between a right eye image and a left eye image, edge detecting means receiving a clock having a second frequency higher than the first frequency for detecting an edge of the signal representing switching by the clock, means for counting the clock having the second frequency on the basis of the detected edge, and means for generating the signal representing distinction between a right eye image and a left eye image on the basis of the value of counted clocks.
According to the above-mentioned construction, the signal representing distinction between a right eye image and a left eye image is generated on the basis of the clock having the second frequency higher than the first frequency, so that jitter is made smaller, as compared with that in such construction that the signal representing distinction between a right eye image and a left eye image is generated on the basis of the clock having the first frequency (corresponding to construction shown in FIG. 16).
In the above-mentioned construction, the spatial transmission signal transmitting apparatus comprises means for converting the clock having the second frequency into the clock having the first frequency, so that the whole of the apparatus, including the means, may be integrated.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.